Cinnamic acid rescues behavioral deficits in a mouse model of traumatic brain injury by targeting miR-455-3p/HDAC2.

Traumatic brain injury (TBI) not only induces physiological disabilities but also leads to cognitive impairment. However, no effective therapeutic approach for TBI-related memory decline exists. In this study, we treated TBI mice with cinnamic acid (CNA) to detect whether CNA is able to rescue the memory deficits induced by TBI and to explore the potential mechanisms.Mice were divided into the following groups: the sham group, the TBI group, the TBI + CNA group and the CNA group. Basic physiological parameters, neurological severity score and brain water content were analyzed. The Morris water maze and inhibitory avoidance step-down task were used to determine learning and memory. Golgi staining was used to measure alterations in dendritic spines. Western blot analysis and a commercial kit were used to detect the content and activity of HDAC2. qPCR was used to detect the relative level of miR-455.CNA did not affect physiological function but effectively restored neurological function and brain edema. CNA alleviated the memory impairments induced by TBI in both the Morris water maze and step-down task. CNA also recovered abnormalities in the synapses of TBI mice by suppressing the activity of HDAC2. Furthermore, CNA did not alter HDAC mRNA because it promoted the expression of miR-455-3p, a miRNA that regulates HDAC2 at the posttranscriptional level.The application of CNA effectively treats TBI-induced memory deficits by increasing miR-455-3p and by inhibiting HDAC2.